Background: Approximately 11,000 Veterans present to a Department of Veterans Affairs Medical Center (VAMC) annually with ischemic stroke/transient ischemic attack (TIA). Effective secondary stroke/TIA prevention includes delivering timely, guideline-concordant management of vascular risk factors. Over the past decade, obstructive sleep apnea (OSA) has been recognized as a potent, underdiagnosed, and inadequately treated risk factor for ischemic stroke. OSA is very common among patients with stroke with a prevalence of 60-70%. Despite being highly prevalent, as many as 70-80% of patients with OSA are neither diagnosed nor treated. Untreated OSA has been associated with poor outcomes among patients with cerebrovascular disease. OSA can be treated with a variety of approaches but the mainstay of therapy is continuous positive airway pressure (CPAP). CPAP has been shown to improve neurological symptoms and functional status among post-stroke patients with OSA, especially when applied early post-stroke. Current stroke/TIA prevention guidelines recommend diagnosing and treating OSA among stroke patients; however, few patients within the Veterans Health Administration (VHA) receive guideline concordant evaluation and management. Objective: Utilizing a Hybrid Type I, randomized, stepped-wedge trial at 6 diverse VAMCs, to implement and evaluate the effectiveness and sustainability of implementation strategies utilized in an Addressing Sleep Apnea Post-stroke (ASAP) program designed to improve diagnosis and management of OSA. Methods: We will initiate the ASAP program at 6 VAMCs that annually care for at least 50 Veterans admitted with a stroke but without a known history of OSA for a fourteen-month intervention period followed by a sustainability period. Effectiveness of the intervention will be measured across two primary (facility-level diagnostic rate and 90-day recurrent vascular event rate) and three secondary domains (treatment rate, PAP adherence, and 90-day all-cause readmission rate). ASAP protocol will include a systems redesign virtual collaborative and data monitoring; implementation strategies will include local adaptation, champions, external facilitation, and audit and feedback. The Consolidated Framework for Implementation Research (CFIR) will be used to evaluate the implementation of the intervention and of the implementation strategies at baseline, at the end of the one-year intervention period, and at the end of the sustainability period. We will construct a business case analysis at the facility-level, including financial components related to the intervention. Hypothesis: We believe that we can implement a sustainable ASAP program across diverse VAMCs which: (1) improves OSA diagnosis, treatment, and 90-day recurrent vascular event rate, and; (2) has a business case favoring intervention sites with the highest baseline recurrent vascular event rate. Conclusion and next steps: Interventions that improve diagnosis and management of OSA among Veterans with stroke/TIA are necessary to improve outcomes; implementation science strategies can assess the uptake and sustainability of this intervention. Since the intervention and implementation strategies have been designed using existing VHA infrastructure, if effective, the program would be ready for scaling system-wide. Results from the business-case analysis for ASAP will be shared with VAMC providers and local leadership who may be interested in implementing this program at their facility. Additionally, an acute sleep service could be adapted other patient populations (e.g., chronic obstructive pulmonary disease), both within and outside of VHA.